Drug-resistant bacterium raises alarms in Chicago

Superbug resistant to most antibiotics, even the strongest

October 22, 2010|By Judith Graham, Tribune reporter

A dangerous, often deadly bacterium resistant to the most powerful antibiotics known to medicine is spreading in Chicago hospitals and nursing homes, prompting an effort to mobilize a regionwide response.

Known as KPC for short, KlebsiellapneumoniaeCarbapenemase bacteria are a drug-resistant form of a common pathogen that was first reported 11 years ago in North Carolina.

Earlier this year, 37 health facilities in Chicago reported an average of 10 KPC cases each, up from an average of four cases in 2009 in 26 facilities, according to a new study presented Friday at the annual meeting of the Infectious Diseases Society of America. The resistant bacterium was first identified in Chicago in December 2007.

"Although the number of infections is small, the fact that so many places are seeing KPCs is very concerning," said Dr. Robert Weinstein, interim chairman of the department of medicine at Stroger Hospital and chief operating officer of the Ruth M. Rothstein CORE Center for HIV/AIDS at the Cook County Health System.

"This is a considerable threat that requires a coordinated response," he said.

While it is unclear how many people have died in Chicago from KPC, studies suggest that the germ kills about 40 percent of people who become infected, according to Dr. Arjun Srinivasan, a medical epidemiologist with the U.S. Centers for Disease Control and Prevention. Typically, these are older, frail patients with multiple medical problems and compromised immune systems.

Klebsiella bacteria live in the gut and can sicken people when they enter the body through other avenues — often intravenous catheters inserted in the urinary tract or blood vessels of seriously ill patients. They're part of a class of organisms known as Gram-negative bacteria, whose best-known member is Escherichia coli, or E. coli.

Over the last decade, Gram-negative bacteria have begun to evolve resistance to drugs once commonly used to fight them as well as to the drugs called carbapenems — medications of last resort that are used to treat infections that don't respond to other interventions.

"These are the most potent antibiotics available," said Dr. Mary Hayden, director of clinical microbiology at Rush University Medical Center and an author of the new study.

Another drug-resistant Gram-negative bacterium originating in India made headlines around the world in September when disease trackers noted its emergence in Europe and the U.S. That organism carries a carbapenem-disabling gene known as NDM-1, which experts worry might be transferred to other pathogens and hasten drug resistance.

Today, 8 percent of all Klebsiella infections in the U.S. involve drug-resistant forms of the bacteria, and cases have been discovered in 35 states. "This is a growing problem" not only in the U.S. but across the world, said Srinivasan of the CDC.

An outbreak of KPC in Rio de Janeiro this year claimed 18 lives. The epicenter for infections in the U.S. is New York.

In Chicago, researchers found that 75 percent of patients who tested positive for KPC came from nursing homes or other facilities serving people with long-term, chronic illnesses.

"We think long-term care settings may be a significant reservoir of this organism," Hayden said.

KPC bacteria are transmitted through physical contact with unclean surfaces or equipment or with health care workers who have not washed their hands, experts said. For many people who become infected, the only therapy is an old antibiotic, colistin, that can be highly toxic to the kidneys.

"If there is an abscess, we'll drain it, or if a central line is infected, we'll remove it," Hayden said. "But treatment is very difficult."

All infections have been confined to medical institutions, and healthy people do not need to worry about picking up the bacterium in the community, Srinivasan said.

For Chicago hospitals and nursing homes, the challenge is to contain the spread of KPC bacteria. That involves identifying patients who may be harboring the organism in their bodies, isolating them from other patients and making sure doctors and nurses wear gowns and gloves when they enter their rooms, Hayden said.

It also means making sure that when patients carrying KPC bacteria are transferred from one medical institution to another — say from a nursing home to a hospital — their status is clearly communicated so precautionary measures can be taken, she said.

"We need more infection-control resources to fight these bacteria," said Dr. Susan Gerber, associate medical director of the Cook County Department of Public Health.

She said her department has begun working with Chicago and state public health officials to educate medical providers about the threat posed by drug-resistant Gram-negative organisms, noting that "we all recognize that we're in this together."